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The Mute Swan (Cygnus olor) is a species native to Europe, North Africa, and southern Asia. Introduced into the United States in the late 1800′s by aviculturists, Mute Swans escaped and spread along the Atlantic coast. Besides the rapid expansion of their range, they have increased dramatically in numbers and now total over 10,000 in the Atlantic Flyway. Most notably, the Rhode Island population has increased by 500 birds since 1986. Although mute swans are considered beautiful by many, they have the potential to negatively affect native habitats and native waterfowl. A study of the effects of herbivory by Mute Swans is now ongoing in Rhode Island. Preliminary results of this study indicate that Mute Swans can greatly affect the growth of submerged aquatic vegetation that serves as a food base for migratory waterfowl. Mute Swan numbers in the state are controlled by an intensive egg shaking program carried out by D.E.M. wildlife biologists. Rhode Island’s Mute Swan population continues to grow, however, because of immigration and the inability to control 100% of the nests. We will review Rhode Island’s Mute Swan population status, control program, and projections of future growth.

Radio telemetry is frequently used to locate the position of animals in wildlife ecology research. In most circumstances, there is a certain amount of error about each telemetry location. Sources of error include distortion of radio transmitter signals from rough topography, human error in locating the radio signal, and errors associated with deriving a geographic coordinate for a fix (e.g., extrapolation from a map, LORAN, GPS). For example, the empirically-derived 90% circular error probability (CEP) radius for telemetry fixes of mule deer in chaparral habitat in southern California was 177m (Nicholson, 1994) and the 95% CEP for mountain sheep in the Sonoran desert was 1,000m (Andrew, 1994). Geographic Information Systems (GIS) is an obvious tool to assess habitat relationships using telemetry data. Commonly used habitat datasets in such analyses include terrain, vegetation, hydrography, land use, and distributions of key resources (e.g., water holes, nest sites, sources of disturbance). The minimum discernible patch size of habitat data can vary immensely. For example, aspect data derived from a 1:24,000 DEM using GRID will consist of 900 m2 patches; whereas, vegetation data taken from 1:24,000 aerial photography might yield habitat patches with minimum polygon sizes measured in square kilometers! The purpose of our study is to determine the extent to which scale differences (or asymmetries) in siting error and patch size render habitat analyses impossible. We are using ARC/INFO’s GRID module to simulate conditions of varying patch size, CEP size, and levels of habitat selection. For each unique suite of parameters, we are measuring the point at which variation in the data overwhelm patterns resulting from habitat selection.

Availability of optimal brood habitat can influence poult survival and be a limiting factor for some turkey populations. Thus, we studied radio-marked eastern wild turkey (Meleagris gallopavo sylvestris) hens in southern New England to determine home range and habitat use. Six hens without and 10 hens with broods were monitored during the first 6 weeks post-hatching. Mean clutch size was 10.1 + 2.4 and poult mortality during the first 6 weeks was 80%. Mean home range size for all hens was 482 + 304 ha; brood home range (717 + 212 ha) was significantly larger (P < 0.05) than nonbrood home range (349 + 121 ha). Increased brood range was linked to marginal brood habitat. Habitat use differed (P < 0.001) between brood and nonbrood hens and differed (P < 0.01) from availability. Brood hens preferred old field while nonbrood hens preferred deciduous forest. Both groups avoided coniferous forest and forested wetland. Brood hens used habitats with lower tree densities, closer to edge and buildings, and with greater ground cover than did nonbrood hens. Preferred brood rearing areas occupied a small percentage of overall home range. The small amount of adequate brood range may be a limiting factor to this population.

The objectives of this study are to (1) create a GIS-based method for assessing the relative capability of individual wetlands to support a diversity and abundance of wildlife, and (2) to apply the method to the wetlands of the Pawcatuck River watershed in southwestern Rhode Island. The wetlands database used in our analysis includes all nontidal freshwater wetlands and deepwater habitats 0.1 ha and larger; ten habitat classes are represented. Our habitat evaluation model assesses both the internal characteristics of a wetland unit (i.e., content attributes) and its context, or setting, in the landscape (i.e., context attributes). Content attributes include wetland size, wetland class diversity, wetland class rarity, and wetland class edge complexity. Context attributes include hydrologic setting (the degree of association with lakes or major rivers), surrounding upland habitat, wetland juxtaposition (proximity to other wetlands and deepwater habitats), and contribution to local wetland diversity and abundance. This evaluation method and data for the Pawcatuck River watershed will be incorporated into an ArcView-based visualization and query system for use by regulatory officials in the Rhode Island Department of Environmental Management. The ultimate goal of this research is to characterize all freshwater wetlands in Rhode Island according to these criteria.

Disturbance Effects on the Stability of Plant Community Structure in a Rhode Island Salt Marsh

The degree to which natural disturbance changes plant community structure depends on both the disturbance potential (e.g., intensity, type, and frequency), and the resistance of species and phenotypes to mortality caused by disturbance. Our study focused on the frequency of wrack-burial disturbance and the resistance of salt marsh plants to wrack burial. We established plots with and without wrack covers in three areas of a salt marsh in Rumstick Cove, Rhode Island. Long term field observations indicated that these three areas differed significantly in the extent and frequency of wrack coverage. Our data indicated that the resistance to burial by a dominant perennial, Black Rush, (Juncus gerardii) was lowest in the least disturbed marsh area. Consequently, experimental wrack disturbances promoted the growth and establishment of opportunistic species such as salt grass and saltwort to the greatest extent in this area. We suggest that the extent and frequency of wrack burial is positively correlated with net productivity of black rush and that more productive stands of Black Rush may be more resistant to wrack disturbance.

The Ringed Boghaunter Dragonfly, Williamsonia lintneri Hagen, is a rare local species currently recommended for federal listing as “Threatened.” It has been found historically in about 20 sites in the Northeast US. Three sites in Rhode Island were confirmed in 1993 and 14 additional sites have been found since then by the Natural Heritage Program and The Nature Conservancy. The new sites are smaller and wetter than historical sites and are concentrated in Richmond and Exeter, Rhode Island. One site in Richmond, supporting the largest population yet recorded, abuts a housing development. Historical documents list 57 species of dragonflies and damselflies from Rhode Island. Collections from 1992 through 1994 confirm most of these and add about 20 additional species to the local record.

Recognizing that geology is an essential aspect of natural history and a significant influence on ecology, here are presented two new compilations that provide fundamental geologic observations:
a) A 1993 surficial (glacial geology) map (scale, 1:250,000) showing areas in Rhode Island covered with sand and gravel, and till, respectively.
b) A 1994 bedrock map of Rhode Island (scale, 1:100,000) showing the types of rocks that underlie the glacial deposits.
Such maps help to identify areas of special character that should be preserved as part of our natural heritage. They also provide bases for diverse studies such as radon risk-potential, resource availability, etc. The data are in digital format and can be used in conjunction with all other types of digitized data. For example the different chemical compositions of surficial (regolith) and bedrock units obviously influence the composition of soil and groundwater and thus affect the biological communities in contact with them; a comparison of the characteristics of geological units and the distribution of biological systems should prove informative.

We studied nesting biology of female Sharp-tailed Sparrows (Ammodramus caudacutus) in a salt marsh with restricted tidal flow at Galilee, Rhode Island in 1993 and 1994. Based on 21 nests found in 1993 and 45 found in 1994, crude rates of success (% nests in which > 1 young fledged) were 95.2% and 73.3%, respectively. Corrected for days of exposure, success was 75.8% in 1993 and 53.6% in 1994. These rates are higher than other estimates of nesting success for this species in undisturbed salt marshes in Rhode Island and New York. Most (>60%) nest failures in these studies were attributed to flooding during high tides. Because high tides are attenuated at Galilee, the 13 unsuccessful nests in the 2 years failed because of mammalian predation (38.5%), avian predation (30.8%), flooding (23.1%), and starvation (7.7%). Females fledged 2.51 + 1.62 young/nest and 4.14 + 2.32 young/female. We will continue to monitor nesting during the planned restoration of the Galilee Marsh, and possible effects of the restoration on nesting of Sharp-tailed Sparrows will be discussed.

Sediments of the Providence River concentrate most chemicals and create a suite of problems. The river sediments also possess the potential to transform chemicals when aerobic advective processes (water circulation and bioturbation) support diverse microbial functions. Thus, when all components work well excess carbon compounds are collected, detoxified, and converted to carbon dioxide and biomass. It is thus hypothesized that a mature, diverse, and robust infaunal community is key to benthic carbon remineralization, including degradation of toxics, and in governing the fate of trace metals. The specific components include a bioturbation community that advects both sediment and seawater and a microbial community that exploits these mixing processes to metabolize carbon and transform metals. As a result of deep burrowing and irrigation of anoxic areas, vertical turnover of sediment, and mechanical-digestive processing by deposit-feeding, microbial transformation reaches full potential.

Bioturbation has been shown to directly affect contaminant concentrations. Emerson et al. (1984) showed that bioirrigation was the major transport variable for trace metals through the release of sulfide and thus the release of insoluble metal sulfides. Riedel et al. (1987) showed that the irrigated burrows of Nereis increased dissolved arsenic release from anoxic sediment 5-fold over physical processes, including storm resuspension. Spies et al. (e.g., 1979) has shown that a natural oil seep is consumed by a microbial-infaunal ecosystem. Several studies have demonstrated the microbial degradation of aliphatics, PAH’s (Gardner et al., 1979) and a wide variety of organic compounds including pesticides, PCB’s, and dioxins (Davis, in review).

If a mature, robust, and diverse benthic community can significantly recycle carbon and detoxify chemicals why isn’t it happening in so many harbors and estuaries? Is there a master variable, such as stable oxygen concentration in bottom waters, that limits these processes? If so, can dissolved oxygen be economically maintained through passive environmental engineering (no external energy or moving parts) so that existing circulation patterns such as tidal flow can maximize vertical circulation and aeration? Can ebb and flood channel flow be maximized? Can barriers be modified to enhance horizontal and vertical exchange? It is time to demonstrate that a stable aerobic system may best recover large contaminated sediment reservoirs such as Providence, Boston, or New Bedford, cheaply and more effectively than dredging, burial, or incineration.

Avian community characteristics and habitat relationships were investigated in three mature red maple swamps and adjacent upland forests in Washington County, Rhode Island during the 1991 and 1992 breeding seasons. Bird surveys were conducted and habitat measurements were taken in 12 60 m diameter plots distributed evenly among three transects and four habitat zones at each site. Cluster analysis and univariate ANOVA revealed a distinct break in habitat characteristics between upland and wetland zones at each site, but there was great variation in the details of habitat structure among the sites. Similarity index calculations showed that the composition of the avian community changed predictably from one end of the moisture gradient to the other at two sites. Many of the most common species in both wetland and upland zones were identical; however, the relative numbers of individuals of each species changed in a consistent manner along the gradient. Consistent patterns were lacking for avian species richness, relative abundance, and heterogeneity. Low (< 25 cm) herb cover was the habitat variable that was most strongly correlated with avian community characteristics.

The Use of Color Infrared Digital Orthophotography To Map Vegetation on Block Island, Rhode Island

We used near-infrared digital orthophotography and three collateral data sets to model ecological communities on Block Island, Rhode Island. Aerial photography of the island was taken on May 19, 1992 at a nominal scale of 1:40,000. The photography was scanned and differentially rectified. The resulting dataset was comprised of three spectral bands and had a pixel dimension of 1.27m. The three bands of data were used as independent variables in the model. The GRID Module of ARC/INFO was used to analyze the raster data sets. Three textural variables were developed by calculating the standard deviation within a 10 meter radius of every pixel for each of the three imagery bands. The terrain model that was used to create the orthoimagery of Block Island was also used to derive SLOPE and ASPECT data. Soil Survey data were used to create a DRAINAGE CLASS dataset and this was used to distinguish wetland from upland vegetation. Overall there were 9 independent variables and one dependent variable (vegetation class) in the model. We used linear discrimnant analysis to classify 14 vegetation models within 6 discrete land cover classes on Block Island, Rhode Island. The Mean Classification Accuracy for training data was 80.5 percent for training data and 55.2 percent for validation data. Overall Classification Accuracy was 77.1 percent for training data and 56.6 percent for validation data. The ecological variable DRAINAGE CLASS dominated the model and explained the most variation in vegetation class.

Density of Nesting Forest Birds in Southern Rhode Island Forests: The First Five Years

I initiated a intensive monitoring program for breeding birds in southern Rhode Island forests in 1990. The program was intended to complement existing broad-scale monitoring being conducted by Division of Fish, Wildlife, and Estuarine Resources biologists. The methodology used is that of the Breeding Bird Census program coordinated by the Cornell Laboratory of Ornithology. Plots are established on protected public and private lands where human disturbance is minimal. Trained volunteers and undergraduate students use spot-mapping to census breeding birds on 10-11 ha plots in several forest types. I interpret all field maps and generate relative density estimates. Vegetation is sampled every 5 years using standard methods to track habitat changes. Initially, the program included 3 plots, but this has been expanded to 7 as the volunteer pool has grown. Data for each year are sent to the Laboratory of Ornithology for inclusion in their database, but is also available for local use. So far, data have been used to describe the effects of landscape pattern on bird species occurrence. Trends in density of common species will be discussed in light of regional population trends from more extensive monitoring programs.

Nesting Status of the Black-throated Blue Warbler in Rhode Island, and Its Value as an Umbrella Species for Conserving Forest Biodiversity

The Black-throated Blue Warbler (Dendroica caerulescens) has historically been considered one of Rhode Island’s rarest breeding birds. Initially discovered nesting in 1921 this species was regularly reported through the 1940′s primarily from northwestern parts of the state. In subsequent years it disappeared from the ornithological record as a nester, and field work associated with the Rhode Island Breeding Bird Atlas (1981- 1987) failed to document any evidence of nesting. The location of a territorial male in 1988, and other records including a mated pair discovered in 1993, suggested the presence of a population of this forest-nesting warbler in the vicinity of Sprague Hill in western Glocester.

In 1994, a series of survey transects was established to determine the breeding avifauna of this region with particular emphasis on defining the extent of the Black-throated Blue population. Each transect consisted of a series of points spaced at 250-meter intervals, with each point sampled during the nesting season using a standard point-count methodology. A total of 13 male Black-throated Blue Warblers were located in the study area, and additional survey work confirmed 5 nesting attempts.

The Black-throated Blue Warbler requires large contiguous tracts of unfragmented forest for nesting habitat. A ground-nesting species, it can be particularly vulnerable to increased predation and cowbird parasitism associated with forest fragmentation. The continued presence of this species in Rhode Island is dependent on the perpetuation of extensive forested tracts in northwestern parts of the state. The Black-throated Blue Warbler can thus serve as an umbrella species under which many other forest-inhabiting plants and animals may be preserved.

The Double-crested Cormorant (Phalacrocorax auritus) is a large aquatic bird inhabiting marine coastal waters and nearby ponds. Numbers have been increasing on the New England coast since the 1920′s and a breeding population has been present in Rhode Island since 1981. So far local nesting has been mainly confined to small or medium-sized islands in or near Narragansett Bay. There were six main Rhode Island colonies in 1994, and four other sites have been used occasionally. Two sites were newly occupied in 1994.

The tremendous increase of this northern breeder appears to be largely the result of recent freedom from long-term human exploitation and efforts at controlling its population in Maine. Its arrival as a breeder is probably a reclamation of a former segment of its natural range, but its impact on other marine and estuarine biota deserves more careful study.

Data will be presented showing the population increase on various islands. Transitions from open rocky islands to larger forested islands will be noted as the species has occupied portions of the outer coast and moved into Narragansett Bay. Data will be presented on competition in various forms between cormorants and herons nesting on the same islands.

Mesozooplankton Distribution and Abundance in the Providence River
and West Passage of Narragansett Bay, 1985-1987

We sampled zooplankton in Narragansett Bay along a seven-station transect from Fields Point to Wickford, during 60 cruises between 25 July 1985 to 29 June, using 153 µm nets, as part of a study of plankton dynamics spurred by the “brown tide” outbreak of 1985. On average, phytoplankton biomass was greatest at the mouth of the Providence River but zooplankton biomass (as mg dry wt. . m-3) reached a maximum in the central West Passage. Most zooplankton taxa occurred at all stations, but their proportional numerical abundance changed greatly along the transect. Acartia tonsa and A. hudsonica together comprised 52-68% of the zooplankton. A. hudsonica, with several other winter-spring copepod species, and the cladocerans Evadne nordmanni and Podon polyphemoides were sharply reduced in abundance in the Providence River, compared to the West Passage while A. tonsa and other summer-fall copepod species were more evenly distributed. As a group, benthic invertebrate larvae were most abundant in the Providence River and decreased down the Bay. In July-October 1985, cladocerans were absent, and copepods were much less abundant than during the same period in 1986. Biotic and abiotic factors affecting these spatial and temporal patterns will be discussed.

Growth and survival of most plants depend upon the ability of their roots to form a symbiotic association
(= “mycorrhiza”) with certain soil fungi. Studies by URI botanists working in Rhode Island and Massachusetts and in the only tropical rainforest in the United States have demonstrated the vital importance of these unusual fungi. Mycorrhizal fungi are essential for conservation of endangered plant species and for restoration of coastal sand dunes, and they enhance the growth and water-use efficiency of turf on golf greens while decreasing fertilizer and pesticide requirements.

This fall, Rhode Island Sea Grant will publish A Guide to Rhode Island’s Natural Places, a 216-page guide to sites of environmental interest throughout the state. Detailed descriptions are provided of over 180 sites owned and managed by state, federal, and municipal agencies, and nonprofit conservation organizations.

Based on the Environmental Education Field Guide to Rhode Island, first published in 1973 by Sea Grant, A Guide to Rhode Island’s Natural Places is designed for the growing numbers of the state’s residents and tourists interested in increasing their knowledge of the state’s natural heritage. In addition to the descriptions, the guide suggests an activity or question for further inquiry for each site. Thirty informational boxes provide more in-depth information on a wide range of environmental topics, from Rhode Island’s geology to a variety of habitats. Extensive appendices provide lists of plant and animal species found in Rhode Island, along with resources for further information, and tips on enjoyment and conservation of the state’s environment. The guide is richly illustrated with accurate pen-and-ink drawings of a variety of plant and animal species.

Trends in Population of Deer Ticks, Ixodes scapularis, on Prudence Island, Rhode Island and Fire Island, New York

Populations of nymphal deer ticks, Ixodes scapularis (Acari: Ixodidae) were sampled by flagging on Prudence Island, RI from 1987-1992 and at Talisman on Fire Island, New York from 1986 to 1994. Yearly population trends matched closely in years when data were available from both sites, suggesting that geographically broadscale factors regulate population fluctuations in this species. Trends in tick populations did not match deer populations, which increased steadily on Fire Island. However, high tick populations in 1992 and 1994 could represent a delayed response to increasing deer densities. Preliminary key-factor analyses suggest density-independence for the Fire Island tick population, but density-dependent population regulation on Prudence Island. Possible mechanisms for regulation of tick populations at these sites will be discussed.

We studied habitat utilization and behavior of Piping Plover (Charadrius melodus) chicks on Goosewing Beach. During the two year study, we examined the effects of habitat availability and human disturbance on chick behavior and fledging success.

Chick activity budgets collected in 1993 indicate that chicks with access to mudflat habitat (augmented by hand-breaching of the salt-pond behind Goosewing Beach) spent significantly more time engaged in feeding and maintenance behaviors, and less time disturbed and in other behaviors, compared to chicks limited to the beachfront and dunes. Similarly, during activity budgets without disturbance, chicks spent significantly more time feeding compared to activity budgets during which a disturbance occurred.

Combining data from 1993 and 1994, chick survivorship (chicks fledged/chicks hatched) for chicks with access to mudflats (80.5%) was significantly higher than survivorship of chicks without access to mudflats (35.7%; G=12.5; df=1; p<0.01). Mean fledging success of broods with access to mudflats was 3.0 chicks/pair (sd=1.3; n=11) as compared with 1.4 chicks/pair for broods limited to the beachfront and dunes (sd=1.1; n=7; t=2.56; p=0.02). Though these data are preliminary, management to increase availability of mudflat habitat at nesting sites might significantly benefit Piping plovers by increasing chick survivorship and fledging success.

I studied the only known major nesting population of diamondback terrapins (Malaclemys terrapin) in Rhode Island at Nockum Hill Nature Reserve, Barrington, Bristol County, and characterized aspects of the nesting behavior and ecology of this population, described nest site habitat characteristics and factors affecting nest success, and compared my findings to other described Malaclemys populations. A total of 241 nests was found at Nockum Hill in 1993. Terrapins tended to nest in the morning and near the time of high tide. Mammalian predators, primarily raccoons, destroyed 75 of 86 monitored nests. Forty-five percent of the surviving clutches were oviposited in the first week of the nesting season. Terrapins preferred to nest in areas containing < 5% vegetative cover, but nest success was not related to percent vegetation, percent shrubs, and/or percent slope at and surrounding the nest site. Nesting females in Rhode Island were larger in body size, and laid fewer but larger clutches over a shorter nesting season than terrapins in more southern locations. Terrapins living in northern latitudes are apparently constrained by a short nesting season, and therefore individuals must lay all eggs of the season in only one or two clutches.

Many macroinvertebrates spend the majority of their lives as larvae in streams. Changes in water quality may effect the aquatic population which may be reflected by the macroinvertebrate populations. Freshwater macroinvertebrates have been monitored for the past four years in Rhode Island at forty five sites. Over 150 species have been enumerated. Although the macrofaunal density and species composition differed at each location, the use of a standardized sampling protocol from the EPA enabled comparisons of the stations within a single sample season and from year to year. Following the fourth year of sampling, trends are developing which may enable macroinvertebrates to be used as an indicators of a stream’s health.

The University of Rhode Island Cooperative Extension’s (URI CE) Watershed Watch program is a statewide volunteer ecological monitoring program that focuses on providing current information on the water quality of surface water resources throughout Rhode Island, including lakes, ponds, rivers and streams. The heart of the program is the weekly measurements taken by approximately 250 trained volunteer monitors. Watershed Watch is a partnership between URI CE, the Rhode Island Department of Environmental Management and local organizations. URI CE, through the Department of Natural Resources Science, provides professional staff support, laboratory facilities, and technical expertise. The program also relies on the time and financial support of a number of organizations throughout the state. These organizations include lake and watershed associations, local and statewide environmental organizations, a number of municipalities, and the Narragansett Indian Tribe. These organizations determine which water bodies are to be monitored and helps to recruit the volunteers. These local sponsors pay to participate in the program. Watershed Watch provides all the monitoring equipment, supplies, and training, as well as water quality data collection, analysis and reports.

The salt marsh is a common terrestrial community in Rhode Island. Salt marshes of Rhode Island are characterized by striking plant zonation along elevational gradients. Lower elevations are subject to frequent tidal flooding that produces anoxic, waterlogged soils with high salinities. At higher elevations, tidal inundation is less frequent and the soil is wellÝdrained, aerated, and lower in salinity. These gradients produce striking variability in plant quality and stature which can have dramatic effects on higher trophic levels. Over the last few years, we have studied common marsh plant species and their associated insect herbivores to understand the influence of physical stress to higher trophic levels. Specifically, we have concentrated on two common plantÝherbivore associations: (1) the Saltmarsh Elder, Iva frutescens, and the dark brown aphid, Uroleucon ambrosiae, (2) the Seaside Goldenrod, Solidago sempervirens, and the leaf beetle, Microrhopala vittata. We found, in both cases, that insect abundance is not only dependent on the physical conditions in which its host plant is exposed but also on the surrounding plants within the host plants’ neighborhood. Simple experiments in which neighboring plants were removed from around host plants showed that local extinction of the herbivores is possible within one season.

Well over 200 species of phytoplankton are found in Narragansett Bay. Despite over 40 years of continuous research on the Bay flora, the total biodiversity is unknown; certainly several undescribed new species are present, as are several known toxic species which fortunately have not as yet cause public health problems.

Over 60% of the phytoplankton species are diatoms. With financial support of the National Science Foundation’s Biotic Surveys and Inventories program, we are beginning the preparation of a manual for identification of plankton diatoms in our region, emphasizing Narragansett Bay, but including the area from the Gulf of Maine to Cape Hatteras. Despite the overwhelming importance of diatoms as primary producers in the food web, there is currently no single source that can be used to key out and identify local species. In addition to a book, the results of our work will ultimately be available as a CD-ROM disc and as computer-accessible data files.

Accurate and up-to-date positional data are an important component in the inventory and monitoring of natural systems. GPS is a technology that enables one to obtain accurate, repeatable, and rapid positional information. Its ease of use, compact size, portability, and decreasing cost has helped it gain widespread use in natural resource applications. In contrast to other conventional survey techniques where line-of-sight to a known control point is necessary, GPS only requires that there be adequate celestial visibility to receive radio signals broadcasted by a constellation of earth-orbiting satellites. Through timing and ranging of signals from 4 or more satellites, a portable ground-based receiver calculates and displays positions in latitude/longitude or comparable coordinate units. With navigation-grade equipment (~$3,000), raw GPS data will be within 100 meters of the true position 95 percent of the time. Using special data processing techniques, raw data can be refined to accuracy levels of 10 meters or less. GPS data are readily integrated into geographic information systems where they can be archived, overlaid, and analyzed relative to existing spatial information.

In Rhode Island, portable GPS offers a tremendous advantage in collecting positional information on individual species, habitats, or phenomena that was otherwise not possible in the past using conventional techniques (e.g., surveying, map approximation). GPS field data can be markedly improved using information obtained from a fixed GPS base station accessible free-of-charge from a computerized bulletin board system operated by The URI Department of Natural Resources Science, Cooperative Extension. It is also possible to use GPS to revisit sampling sites throughout most of Rhode Island by utilizing the signal from a real-time GPS radio beacon operated by the U.S. Coast Guard at Montauk Point, NY. Although GPS has become easier to use, it is not a turn-key technology. There are many aspects of GPS that demand consideration in order to ensure successful data collection in the field. Adequate training and understanding of the technology is a must.

Investigations of a Metapopulation of the Bog Copper Butterfly in Richmond, Rhode Island

The Bog Copper (Lycaena epixanthe) (Lepidoptera: Lycaenidae) occurs in saturated bogs and fens where the obligate larval host plant, wild cranberry (Vaccinium macrocarpon and V. oxycoccos), grows. This butterfly appears to exist in southern Rhode Island as a metapopulation, or aggregation of local colonies experiencing occasional gene flow between sites. The long-term persistence of a metapopulation in the face of demographic stochasticity and environmental catastrophies depends on the presence of sufficiently large “reservoir” populations able to supply colonists to smaller patches, and on the spatial arrangement of habitats which controls the success of dispersal over an inhospitable matrix.

A detailed Geographic Information System database was used to identify over 70 patches of bog and fen habitat in Richmond. Of these, about 50 supported the host plant. Visits to suitable sites in 1993 revealed a pattern of butterfly occupancy which can be analyzed on the basis of bog/fen size, cranberry patch size, habitat isolation, and proximity to rivers and streams. Visits in 1994 indicated temporal changes in occupancy: extirpation of populations due to succession and decline of hostplant vigor, and (re)colonization of new sites following the removal of environmental stress.

Many states have established buffer zones around wetlands to neutralize the impact of adjacent landuses. These buffer zones may not be based on knowledge of the effects of bordering landuse on wetland wildlife, specifically avian reproductive success. We need to know the distance at which nesting success in the wetlands is unaffected by proximity to adjacent upland habitat to establish meaningful development guidelines for leaving buffer zones around these protected areas. This study examined the effect of upland habitat on predation of artificial ground nests in Red Maple swamps. During July-August 1993, the daily survival of nests along the swamp edge bordered by forested upland habitat was 0.98. Along the swamp edge bordered by nonforested upland habitat, the daily survival rate of nests was 0.95. These daily survival rates were different (z = 2.82; P = 0.002). Proximity to adjacent nonforested upland seems to have a strong influence on artificial ground nest predation rates. During May-August 1994, artificial nests were placed at different distances from the wetland boundary. These results will be reported at this conference.

The quality of Rhode Island’s coastal ponds and near shore waters along the south coast is directly affected by the various land uses and human population pressures in the associated watersheds. For this project the authors used data from the University of Rhode Island’s Environmental Data Center and the Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP), in conjunction with the Arc/InfoÈ Geographical Information System (GIS), to explore possible relationships between coastal water quality and various watershed stressors. South coast population and land use information are displayed for each watershed and with distance from the shoreline. For the total south shore watershed, the major land use categories are residential and forest/brush land, followed by agriculture. Closer to the coast, residential land use appears to be greater while forest/brush lands predominate further inland. Both the total population and population density increases dramatically from west to east but, surprisingly, population density does not appear to be a function of distance from the coast. None of the coastal (off shore) EMAP stations exhibit degraded benthic conditions, indicating no widespread problems. However, Point Judith and Quonochontaug Ponds, both associated with muddy, high organic content sediments, did show degraded benthic conditions.

The wolf spider Pardosa lapidicina (Lycosidae) exploits the entire intertidal of bare cobble beaches in Rhode Island, sometimes moving over 40 m during a tidal cycle. It does not submerge as the tide rises, but retreats above the tide. It may reach densities of 40/m of shore line in early fall, making it an important consumer in the intertidal. Its prey includes Diptera, Collembola, and amphipods, all of which inhabit, or feed heavily in, the intertidal zone. This species also occupies the upper reaches of cobble beaches containing a mid-tidal, fringing Spartina marsh, but does not penetrate this vegetation to the cobbles below. However, population densities do not differ systematically between areas without and with fringing Spartina. During most of the spring, summer, and fall P. lapidicina occupies only the beach area, eschewing adjacent woodland, which it only invades during late fall. However, some individuals remain active immediately above the tide line during much of the winter. Overwintering mortality in 1993-94 was about 45%. Larger conspecifics are probably their major predators, but pompilid wasps and jumping spiders also take these spiders.

The American Oystercatcher, Haematopus palliatus palliatus (Temminck), is a bird that has newly returned to Rhode Island. Before 1976 it was one of the rarest shore birds on the Rhode Island coast, but has recently reappeared and is nesting in Rhode Island. Oystercatchers in one form or another are found around the world in coastal areas. There are eleven species (Hayman et al., 1986).

Populations of birds that live on the fringe of their ranges are often excellent indicators or monitors of environmental changes because they are frequently sensitive to minor changes in their environment. The successful nesting and production of young in such peripheral populations is often used as an index of the condition or quality of local habitats. The history of the American Oystercatcher’s reappearance as a summer resident in Rhode Island and elsewhere in the Northeast is a success story that will be examined in this report.

The oystercatcher has been observed and their nests recorded in Rhode Island as part of the ongoing colonial nesting bird survey. Their presence will continue to be used in assessing the “health” of Rhode Island’s marine ecosystem. Information presented above and future annual surveys will provide baseline information for this and other species in selecting areas to be set aside for public ownership for the protection of the oystercatcher and many other Rhode Island maritime birds. This survey is funded entirely through the Pitman-Robinson Wildlife Restoration Act, W23R, Rhode Island, which is generated through a hunting sports arms and ammunition manufacturers’ excise tax, i.e. paid by the Rhode Island sportsmen/conservationist.

The Harlequin Duck (Histrionicus histrionicus) has become a species of controversy in Eastern Canada and New England with the release of a status report by the Canadian Wildlife Service, Atlantic Region. This report was submitted to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) for consideration of the eastern North American population as endangered. COSEWIC accepted the harlequin into endangered status April 1990. Historical information on this species is unclear, therefore, it is important to document current population levels and locations. Rhode Island appears to have had 100+ birds within the Narragansett Bay and Sakonnet River areas for the past five years based on RI Audubon Field Note Reports and observations by the US Fish and Wildlife Service. Massachusetts’ population of harlequins in the Martha’s Vineyard/Cape Ann area has numbered 30+ birds for the past ten years (Wayne Petersen, pers. comm.). The largest number of harlequins in New England is found on Isle Au Haut, Maine. The present estimate for this population is 150 birds (Brad Allen, pers. comm.). Additional surveys in the US and Canadian Maritimes are proposed to further document population size of the eastern harlequin and to determine whether current low levels are a cause for concern or reflect redistribution of this historically small population.

Lyme disease is a tick-transmitted borreliosis of humans and domestic animals emerging as one of the most significant threats to public health in north temperate regions of the world. Despite a myriad of studies into the symptomology, causes, and treatment of the disease, few researchers have addressed the spatial aspects of Lyme disease transmission. Indeed, an understanding of the spatial distribution and dynamics of tick vectors and therefore, Lyme disease is lacking. Thus, we sampled the density and spirochete infection rate of the deer tick (Ixodes dammini) at 80 sites throughout Rhode Island, stratified by vegetation type and geographic location in the state (i.e. north, south). Using the complex spatial analysis capabilities of Geographic Information Systems and spatial statistics, we then combined tick distribution data with geographic information on land cover, hydrology, soils, and climatic data to interpolate and predict Lyme disease transmission risk throughout Rhode Island. Currently, efforts are underway to combine information on the location of reported human Lyme disease cases, as well as the density and distribution of vertebrate vector hosts with the above data to better understand the geography of Lyme disease risk.

Many Neotropical migrants show extensive dietary plasticity during stopover periods. Plasticity in diet during stopover occurs in many migrants by shifting from stereotyped breeding season insect diets to other animal or plant matter (e.g., fruit). These seasonal dietary expansions have strong effects on behavior and energetics of passage migrants, as well as implications for conservation of suitable stopover sites. Dietary plasticity results in changes in behavior, such as foraging, habitat selection, and migratory strategy (e. g., stopover length and caged nocturnal migratory activity). Dietary plasticity also exerts strong influence on migrant energy budgets during stopover. Experimental results show that for species adept at assimilating the novel diet types, dietary plasticity significantly increases energy intake and facilitates lipogenesis. For other migrants, use of new diet types may decrease foraging energy expenditure to result in net positive energetic budgets. Data from Nature Conservancy preserves on Block Island confirm strong effects of dietary plasticity on the behavior and energy budgets of passage migrants. The changing biology of Neotropical migrants must be recognized to understand what habitats and factors are most important in their conservation during migration. Until this occurs, a holistic approach to the conservation of migrant birds throughout their annual cycle will not be realized.

From So Simple a Beginning: Natural History at the Providence Athenaeum

Providence Athenaeum
251 Benefit Street, Providence, RI 02903

A series of talks at the Providence Athenaeum will be held this fall, in anticipation of an upcoming bibliography of the library’s collection of natural history. Nineteenth Century Illustrated Natural History Books–a work in progress funded by the Rhode Island Committee for the Humanities–is being prepared. The Providence Athenaeum has a significant number of volumes dealing with the natural world and man’s engagement with it. There is no better way to appreciate the present day environmentalist’s effort to preserve the world’s natural resources than to read the literature of these earlier naturalists. Through this bibliographic effort we hope to provide greater access to our intriguing collection.

The Spotted Turtle (Clemmys guttata) is a widespread and locally common species in Rhode Island, and has never been considered to be a threatened species here. However, several northeastern states, including Maine, New Hampshire, Vermont, and Massachusetts, are concerned about this species due to its limited geographic range, and suspected declines due to habitat loss and increasing mortality factors. Conservation of this species in the Northeast has been hampered by a lack of data regarding demographic structure of populations, population trends, and habitat utilization.

A study of Spotted Turtle population numbers and demographics was begun in Rhode Island during 1992. All wetlands within a 1-mile square study area were intensively surveyed for Spotted Turtles. Each turtle captured was individually marked, aged, weighed, measured, sexed, checked for gravidity, and released where captured. To assess seasonal activity, a consistent trapping methodology was initiated at one site within the study area. To date, 120 individuals (51 males and 69 females) have been marked.

Spotted Turtles appear to function as a metapopulation within the mosaic of habitats available. Although telemetry has not been used in this study, investigations in other states have revealed a great amount of movement within, and utilization of, terrestrial habitats. In Rhode Island, most individuals leave (or are inactive in) wetland habitats by mid-July. Many of these animals probably move significant distances through upland habitats, and most apparently aestivate for several weeks during mid-summer, for reasons which remain speculative. If the proper stimuli for “return” fall movements do not occur, the turtles may have the ability to winter in the upland.

The great niche plasticity exhibited by this species is a great asset in an intact ecosystem, but this species’ great mobility and seasonal utilization of several habitat types renders it vulnerable within a fragmented landscape. Existing regulations to protect wetland habitats do not allow adequate buffers for this species and corridors between remaining habitats are rarely incorporated into local planning efforts. In the absence of complete life-history information and stronger regulations, it is now recognized that greater size of conservation parcels and their contiguity within the landscape will be necessary to maintain the long-term viability of Spotted Turtle populations in Rhode Island.

Nutrient Resorption within a Single Genotype of Privet (Ligustrum ovalifolium Hassk.)

Autumnal resorption is the process by which foliar nutrients are mobilized and sequestered into perennating tissues during senescence. Despite considerable effort to document the ecological and physiological parameters governing resorption, major voids in our understanding exist. In particular, factors influencing variation in resorption efficiencies remain elusive. The manipulation of a large number of genetically identical individuals details the changes in the efficiency of resorption resulting from short term alterations in environmental parameters. Furthermore, information on the inherent level of variability in resorption among genetically identical individuals has been documented.

Natural populations of the native annual Impatiens capensis (jewelweed or touch-me-not) occur locally in light environments ranging from full sun to deep forest shade, and in a wide range of plant densities. Asymmetric competition for light produces strong density-dependent mortality and reproduction in this species, and exerts intense natural selection on seedling traits. Plants respond to crowding with phytochrome-mediated stem elongation. The proportion of chasmogamous (animal-pollinated) to cleistogamous (obligately self-fertilizing) flowers, and thus the outcrossing rate, decreases at high densities and low light levels. Inbreeding depression in Impatiens capensis is intensified by asymmetric competition and increases with distance of the progeny from the parent plant. There is evidence for within-population genetic differentiation and local adaptation on a 10-40m scale. In addition, common garden experiments have revealed dramatic genetic differentiation for a variety of morphological, physiological, and life history traits between nearby populations from open and woodland sites. In particular, lines from woodland populations flower earlier and display reduced sensitivity to vegetation shade. We are currently examining the genetic basis and fitness consequences of phytochrome-mediated shade avoidance responses.

The Wood Duck (Aix sponsa) is the most harvested waterfowl species in the Atlantic flyway. The U.S. Fish and Wildlife Service (USFWS) has developed the Wood Duck Population Monitoring System to acquire population and productivity estimates needed to manage the wood duck more efficiently. The University of Rhode Island, in cooperation with the Rhode Island Department of Environmental Management (RIDEM) and the USFWS, is conducting a Rhode Island nest box monitoring program. In the summer of 1994, we sampled 228 of the approximately 700 wood duck nest boxes on which RIDEM had recent data. We described the habitat surrounding the boxes using the National Wetlands Classification System. Nest box use and productivity were recorded and the data contributed to the USFWS regional database. Wood Ducks occupied 42.4% of the sampled boxes, and 62.6% of these successfully hatched ducks. This summer’s monitoring project is scheduled to continue for 2 more years.

Osprey (Pandion haliaetus), once abundant in Bristol County in the upper Narragansett Bay, experienced a well documented crash in the 1960′s. The use of DDT and its subsequent ban has been the single most important factor affecting the breeding success of ospreys in Rhode Island. Plastic entanglement, human harassment, predation and weather have caused serious losses, especially to young, in localized areas. Current Osprey populations are concentrated in Washington County on high voltage powerlines following the Wood and Pawcatuck River system. Other equally tall poles and towers have been used with great success, reducing animal predation and causing relatively few conflicts with utility owners. Private sector interest has resulted in placement of additional platforms, increasing the likelihood of usage and success by selective placement and monitoring. The increase in the population has hampered the Division’s ability to survey the population, but efforts will be continued as neighboring populations in the Westport River are being impacted by factors unknown.

The Eastern Wild Turkey (Meleagris gallopavo sylvestris), once abundant in Rhode Island prior to European colonization, became extinct from the state by the late 1700′s. Restoration of wild turkey populations in Rhode Island began with a single release of 29 wild trapped Vermont birds into the town of Exeter in 1980. These birds, combined with turkeys release near the state line by Connecticut DEP, formed the nucleus of the state’s population. Trap and transfer operations were reinitiated in 1994 when 48 New York wild turkeys were introduced to three sites with no or low turkey population in order to reestablish the species.

Turkeys have responded well to Rhode Island habitats and in 1994 the population is estimated to be 1000 birds. Cooperator sighting reports used to monitor the distribution of turkeys statewide have been an important tool. In 1993, a total of 73 sightings of wild turkeys were reported from 18 towns across the western half of the state, representing a 28% increase in cooperator reports over 1992. Brood production and survival, important to measuring population growth, was excellent in 1993 and again in 1994. Mean brood size in late summer was 4.3 poults per hen (n=11 broods) in 1993 and 5.0 poults per hen (n=43 broods) in 1994 suggesting nearly 50% survival of young and excellent fall recruitment. Use of annual turkey call count surveys provide information on distribution and peak of gobbling activity. A limited spring turkey (males only) hunting season was initiated in 1986 and annual harvest has increased annually with a total of 43 males harvested in 1994.